Flong for matrices



United States Patent FLONG FOR MATRICES Robert A. Travis, New York, N. Y.

N0 Drawing. Application January 13, 1954,

' Serial No. 403,931

7 Claims. (CI. 22-55) This invention relates to flongs or blanks for matrices to be used in stereotyping. The principal object of the invention is to reduce or eliminate the variation in dimensions and distortion which occurs upon change of moisture content in the flongs now in use and the matrices made therefrom.

The flongs now in general use for the preparation of matrices consist of dense, smooth-surfaced, fibrous layers made from well-beaten wood pulp with a filler of clay. These flongs consist mainly of cellulose fibers which are moisture-absorbent and which change their size on change of moisture content- The linear dimensions of such a flong and a matrix produced therefrom vary on changes in the moisture content. These dimensional changes are difficult to control with the result that there is sometimes distortion, and there is frequently variation in the dimensions of printing plates cast from ,a number of matrices which have been molded in the same mold or in molds of the same dimensions. This is especially disadvantageous in color work where color registration is vital.

The dimensional variation of the present flongs on changes of moisture content is so objectionable in color work that it is customary in high grade color work to adopt time-consuming expedients to reduce moisture content in matrices between the time that they are molded and the time that type metal is cast against them. Thus, when matrices are molded, it' is customary to dry them in the press, and in high grade color work the drying period is often as long as twenty minutes.

I have discovered that mixing a minor proportion of glass fibers with the cellulose fibers of a fiong has the effect of inhibiting motion of the cellulose fibers in the plane of the flong when the fibers are swollen'by the absorption 'of moisture or shrunk by loss of moisture.

I have found that the addition of glass fiberhas the surprising result of reducing the dimensional variation by a percentage very much greater than the percentage of glass fiber introduced. This has been clearly brought out by (1) measuring the large shrinkage which occurs in the initial drying of a newly made flong, and (2) measuring the smaller shrinkage which occurs in the use of a matrix made from the flong.

As illustrative of the results of such measurements, which necessarily vary somewhat with the circumstances under which they are made, I append a table based on a specific set of measurements which I have had made. The table shows the percentage of reduction in shrinkage which was obtained by introducing different percentages of glass fiber of Mt inch length and .00036 inch in diameter into an ordinary flong, as compared with the shrinkage of this ordinary flong containing no glass fiber. In making the measurements of flong shrinkage, the moisture content of a newly made flong was reduced from about 65% to about 2%. In making the measurements of matrix shrinkage, a matrix made from the flong and containing 20% of moisture was molded and heated in the molding press to 300 F. for one minute. The matrix was The large percentage of reduction of shrinkage by a small percentage of glass fibers makes it evident that the glass fibers are not merely stable in the presence of moisture but also have the etfect of inhibiting movement of the cellulose fibers. The exact mechanism by which they produce this efiect cannot be stated with certainty. It seems probable that in the matting together of the glass and cellulose fibers in the making of the flong, the glass fibers are bound together by the cellulose fibers into a sort of inextensible skeleton in which the cellulose fibers are embedded.

This theory is supported by the fact that the degree to which the flong is dimensionally stabilized by the incorporation of glass fibers depends to some extent upon the length and disorientation of the glass fibers. If the fibers are too short or if they are oriented in one direction, they apparently do not form as stable a glass skeleton within the flong. Well disoriented glass fibers longer than the cellulose fibers are needed, and a length materially greater than A; inch is desirable.

My invention, which is based on my discoveries as to the effect of glass fibers in flongs and matrices made from them, consists in mixing a minor proportion of glass fiber with the wood pulp in making a flong to control, reduce and, if desired, even entirely to eliminate dimensional variation of the flong and the matrix made therefrom on moisture changes.

The proportion of glass fiber which is incorporated in the flong in accordance with my invention depends upon the results desired. Very small proportions of glass fiber cause a substantial reduction in the linear shrinkage of the matrix and thus introduce economies by reducing the usual drying time on the press. They have the further advantage of controlling such dimensional changes as occur and reducing or eliminating distortion. By use of a glass fiber content of 20%, complete dimensional stability-is approached on wide changes in moisture content. A still further increase in the glass fiber content has the advantage of insuring complete dimensional stability, but increase of the content above 50% has no further efiect on dimensional stability and may have the disadvantage of making the flong brittle or making its molding surface irregular. For these reasons, I consider a glass fiber content between 20% and 50% as most desirable.

In order that my invention may clearly be understood, I will described specific examples of flongs embodying my invention:

Example 1 The flong consists of a smooth-surfaced sheet of a thickness of 0.03 inch having the following composition: Percent by weight 55 Cellulose fiber Glass fiber 35 Filler 10 Patented Mar. 1, 1955 i The glass fiber consists of glass filaments of the following dimensions:

Diameter inch 0.00012 Length do /2 The filler consists of the clay ordinarily used as a filler in ordinary fiongs of cellulose fiber.

The flong described in this example is made on a cylinder-type flong-making machine. After the wood pulp has been thoroughly beaten and the filler has been added and before the pulp is deposited on the cylinder, the glass fiber is thoroughly mixed with the wood pulp and filler.

After the mixed fibers have" been formed into a thick sheeton the forming cylinder of the machine,-removed from the cylinder and at least partially dried, the sheet is calendered to give it smooth surfaces. After calendering, it has a thickness of 0.03 inch.

After calendering, a smooth facing is applied to one surface of the flong. The facing consists of'an inert-filler such as china clay, talc or ground mica with an adhesive such-as destrine orstarch. It may be applied to the surface by spraying or rolling.

The flong described was compared with an ordinary flong made at the same time With the identical'cellulose fiber and filler. In the first drying in which the moisture content was reduced from about 60% to about 2%, the ordinary flong shrunk of 'an inch in 4 linear inches, which is a linear shrinkage of about 12%. Under the same conditions, the flong containing glass fibers described in this example showed no linear shrinkage.

A flong made in accordance with this example may be made into a matrix in the ordinary manner, that is to say, thefiong is humidified to about 20% moisture content and the coated face is then forced into avprinting plate or engraving under a pressure of 1500 lbs. or more per square inch. After storage and shipment of the matrix thus made, it is used to produce a stereotype plate by first scorching to thoroughly dry it and then casting type metal against it at a temperature of approximately 650 F. In using this flong, long drying on the press after molding, which is usual in color work, may be omitted, as the loss of moisture remaining in the matrix after molding, or absorbed by the matrix from the atmosphere has no effect on the dimensions of the matrix. Thus, at the time'the matrix is used for casting, it has the same dimensions as the plate or engraving against which the flong was molded.

Example 2 The flong consists of a'smooth-surfaced sheet of a thickness of .025 inch having the following composition:

Percent by weight Cellulose fiber 85 Glass fiber 10 Filler 5 The cellulose fiber and the'filler are the same as those' used in Example 1. The glass fiber consists of filaments of the following dimensions:

Diameter inch .00036 In making the flong, care is exercised to distribute the glass fiber thoroughly and to avoid orientation of the glass fiber. The flong is calendered and faced-as in Example 1.

In the initial drying of the flong, in which its moisture content was reduced from about 65% to about 2%, the flong showed a slight but regular shrinkage. In use ofthe flong inan ordinary manner to make a matrix-humidifying it to 20% of moisture, molding and drying'on the press at 300 F. for one minute,sco'rching and then casting-the. matrix 'made from the flong showed a linear shrinkage of not more than one-half of that ofa'fiong containing no glass fiber. This permits reducing the drying time on the press below that required when an ordi' nary flong is used. The shrinkage'causes little or no distortion. -The shrinkage of a number of fiongs' of the same dimensions isuniform so that color plates made from such flongsare of the same dimensionsand therefore/useable for color printing.

- Example 3 This flong is like those of the first two examples excep't'that its composition is as follows:

Percent by weight Cellulose fiber 93 Glass fiber 2 Filler S printing.

My invention requires no change in flong thickness and no change in the filler content offiongs. As in ordinary fiongs the filler content may be from 5% to 25% by weight.

The thickness of the glass fiber filaments is not critical. The thickness of the filaments does not materially affect the dimensional stability of the flong. The use of very fine filaments has the advantage of making the flong dense and very smooth on the surface so that it can take a very accurate impression. On the other hand, the filaments must be strong enough to form a skeleton which will inhibit movements of the cellulose fibers. I have found that filament diameters between .00002 inch and .00055 inch are satisfactory.

It is apparent from the above examples that flongs embodying my invention are not limited-to any particular composition, and thatthey differ from ordinary fiongs merely in that a minor part of the usual cellulose fiber content is replaced by glass fiber to inhibit dimensional changes on the swelling or contraction of the cellulose fibers which occurs when the moisture content changes.

This application is a continuation-in-part of my application filed December 5,1951, Serial No. 260,107, and of my application filed February 20, 1952, Serial No. 272,707, which have been abandoned in favorof this application.

What I claim is:

1. A moisture-absorbent sheet consisting essentially of clay filler and fibrous material, having sufiicient clay filler content and having a surface coating sufficiently smooth to serve as a flong for producing a matrix, the fibrous material containing from 2 to 50%, by weight, of fgilglss fibers and the remainder being essentially cellulose ers.

2. A moisture-absorbent sheet consisting essentially of clay filler and fibrous material, having suflicient clay filler content and having a surface coating sufficiently smooth to serve as a flong for producing a'matrix, the fibrous material containing from 2 to 50%, by weight, of glass fibers and the remainder beingessentially cellulose fibers, the

two kinds of fibers being matted together, and the glass fibers being'longer than the'cellulos'e fibers.

3. A moisture-absorbent sheet'consisting essentially of clay filler and fibrous material, having sufiicient clay filler content and having a surface coating sufliciently smooth to serve as a flong for producing a matrix, the fibrous-material containing from 20 to 50%, by weight, 3% glass fibers and the remainder being essentially cellulose ers.

4. A moisture-absorbent sheet consisting essentially of clay filler and fibrous material, having sufficient clay filler content'and having a surface coating'sufliciently smooth to serve as a flong for producing a matrix, the fibrous material containing from 2 to 50% of glass filaments'of a diameter from .00002'to .00055' inch and a length of more tilan inch, the remainder being'essentially cellulose ers.

5'. A moisture-absorbent sheet consisting essentially-of clay filler and fibrous material, having sufficient clay filler content and having a surface coating sutficiently smooth to serveas a flong for producing amatrix, the fibrous material containing from 20 to 50% 'of glass filaments of a diameter from .00002'to .00055 inch and a length of more than inch, the remainder being essentially cellulose fibers.

6. A flong for producing a dimensionally-stable matrix consisting of a smooth-surfaced sheet of the following composition: glass fibers 20 to 50% by weight, a clay filler about 5 to about 25% by Weight, and cellulose fibers of well-beaten Wood pulp to make 100%.

7. A flong consisting of a calendered sheet of about 0.03 inch in thickness and consisting of cellulose fibers from Well-beaten Wood pulp, a clay filler in a proportion from about 5 to about 25 and glass fibers in a proportion from 20 to 50%, the glass fibers being composed of filaments of a diameter of about one ten-thousandth inch and a length of more than inch.

References Cited in the file of this patent UNITED STATES PATENTS Leppik Apr. 7, 1936 Leppik Dec. 1, 1936 FOREIGN PATENTS Great Britain Mar. 1, 1934 Great Britain Nov. 16, 1939 

